Pooling assessment of homing pigeons during urban and extra-urban flights: an instrumental approach *

The field of biologging has undergone significant advancements, enabling researchers to collect high-resolution data on a range of ecological and biological phenomena. In the context of avian studies, miniaturized biologgers have proven instrumental in investigating flight dynamics, particularly in species such as homing pigeons (Columba Livia). While earlier research has principally classified pigeon flight as either flock or solo only based on release conditions, free-flight scenarios are more complex, involving variations in route choice, pausing behavior and different pooling in comparison to original release conditions. To address this gap, a novel instrumental approach is presented in this paper to automatically detect homing pigeons' flight type and flock size and to take into account modifications of the previous characteristics over urban and extra-urban areas, by equipping homing pigeons with wearable sensors. To deeply characterize pigeons' flight in flock or solo condition above urban and extra-urban areas, wingbeat frequency, peak-to-peak acceleration and ground speed were computed. In comparison to the original releases conditions, in approximately a half of the total releases solo-released pigeons joined the flock and vice versa, indicating a consistent pattern to deviate from the initial release configuration, which may lead to a realistic analyses of solo or pooling behavior during flight.The results show that pigeons flying in flock exhibit a higher wingbeat frequency compared to solo flight modality, while showing an inverse pattern for peak-to-peak acceleration. Comparing urban and non-urban environments, the results show that in extra-urban contexts pigeons exhibit a reduction in wingbeat frequency when flying in flocks. Additionally, they tend to form larger flocks compared to those observed in urban settings.